Survey Shows Low X-ray Danger

Press, Volume CIII, Issue 30542, 10 September 1964, Page 20

Survey Shows Low X-ray Danger

The genetic radiation danger from X-rays and other diagnostic radiation in New Zealand is lower than in any other country which has yet published figures, and the genetic effect on the population is less than a tenth of the effect of the natural background radiation. This is revealed by a survey carried out by a team at the National Radiation Laboratory, Department of Health, under the leadership of Mr B. D. P. Williamson.

The “genetically significant” dose of radiation to the public of New Zealand from diagnostic radiations is lower by about 15 per cent than in Britain, where, other things being equal, a given dose could be expected to be less significant than in New Zealand because of the much greater average number of children borne by New Zealanders than by British people and the much greater proportion of children here than in the British population. All types of diagnostic radiology were taken into account —medical, dental, mass miniature chest, and chiropractic. Private practitioners were visited as well as public and private hospitals. Full co-operation was received from all. The experimenters measured the radiation doses received by the gonads of patients during about 4000 actual examinations in hospitals which do about 80 per cent of all diagnostic examinaIslands Cruise The first school educational cruise of the Pacific Islands, which ended when the Kuala Lumpur berthed at Auckland, is to become an annual event in the August holidays, the promoter said today. On the cruise were 71 schoolboys and eight teachers from Auckland. It was a 17-day cruise, with visits to Tonga, Samoa and Fiji.—(P.A.)

tions carried out in New Zealand. The information so gained was used to calculate the average gonad doses received during particular radiation procedures. A statistical analysis was also made of a sample of 40,000 of the 900,000 carried out yearly in New Zealand, to work out the distribution by age and sex of patients examined. From these data and the average gonad doses for each type of examination, the annual genetic dose was found. The annual genetic dose is that dose which, if given to every member of the population, would give the same genetic effect as the sum of the individual doses actually received. The potential genetic effect of a given dose of radiation is greater in a young person than in an older person, and nil when the age of child expectancy has passed. Other Finding Mr Williamson and his group also carried out a survey of the radiation dose to the population as a whole represented by the exposure of those operating radiation sources. This survey would have been impossible in any other country except, perhaps, Sweden, because no other country has a routine radiation film-test service for all who are occupationally exposed to radiation. The survey showed that the genetic danger to the general population from occupational exposure is less than a tenth of 1 per cent of that of the natural background radiation. The survey did not extend to therapeutic (healing) radiation, or to radioactive isotopes used in diagnostic work. A survey of these may be made later.

Mr Williamson and his colleagues—another physicist, Mr A. C. McEwan, and two technicians, Mr N. F. Paris and Miss M. Farrant—will give the full figures revealed by their survey in the medical press.